| 摘要 |
<P>PROBLEM TO BE SOLVED: To solve the problem that the influence of various aberration, especially the influence of comatic aberration, increases if an F number is made smaller and the size of an optical system is reduced in a conventional optical system. <P>SOLUTION: An image pickup optical system includes, in order from an object side, a first lens having positive refractive power, a second lens having negative refractive power, a third lens having positive refractive power, a fourth lens having positive refractive power and a fifth lens having negative refractive power, has a diaphragm arranged closest to the object, and satisfies the following conditional expression (1) -4.0<(r6+r7)/(r6-r7)<-0.51, where r6 is a paraxial curvature radius of the third lens at the object side and r7 is a paraxial curvature radius of the third lens at the image side. <P>COPYRIGHT: (C)2013,JPO&INPIT |
